function lazyload(){
$('img').each((i,item)=>{
let top = $(item) .offset (). top
let sTop = $(window). height () + $(document).scrollTop()
if(top <= sTop){
let src =$(item).attr('data-src')
$(item).attr("src",src)
}
})
}
let t
lazyload()
$(window).scroll(function(){
if(t) return
t=settimeout (()=>{
lazyload()
t=null
},1000)
})

